Color-changing 'Stained Glass' Made With Energy-storing DSSCs

2014/08/03 00:41
Tetsuo Nozawa, Nikkei Electronics
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A Japanese research group prototyped a stained glass-like panel and lighting apparatus that can generate and store electricity and change their colors.

The group consists of researchers of the Segawa Laboratory of the Research Center for Advanced Science and Technology (RCAST), the University of Tokyo, and Sony Corp. The prototypes were exhibited at PVJapan2014.

The designs of the exhibits were based on hydrangea. The stained glass-like panel and lighting apparatus were named "Annabelle," which means a kind of hydrangea whose flowers are white, and "Hikari," respectively. The lighting apparatus can generate electricity while emitting light, and the generated electricity can be supplied to an external device via a USB port.

Both of the prototypes were designed by using the "ES-DSSC (energy-storable dye-sensitized solar cells)" technology that the Segawa Laboratory has been developing since about 2003. They were made in cooperation with Sony. Initially, rechargeable batteries were mounted on the reverse sides of dye-sensitized solar cells (DSSCs), and the electrodes (counter electrodes) and electrolyte of the DSSCs were shared with the rechargeable batteries.

For the latest prototypes, the research group employed a design that arranges DSSCs and rechargeable batteries on the same plane. In other words, they were used to express different colors for the stained glass-like panel.

One of the features of DSSC has been that it enables to use various pigments to change the designs of panels. This time, the rechargeable batteries also contributed to the design of the panel. Specifically, the color of the batteries changes in accordance with the state of charge because tungsten oxide (WOx) is used for their charge-storage electrodes. When WOx stores electric charge, its color changes from transparent to deep blue (electrochromic effect).

The research group used DSSCs and rechargeable batteries to express the leaves and flowers, respectively, of the hydrangea. When the batteries are out of charge, their colors are almost white. But they will gradually turn deep blue as they charge, expressing the color of hydrangea coming into bloom.

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